Romney goes for the kill on Super Tuesday

David Rothschild, Yahoo! News

Economist

The SignalMarch 5, 2012

We have held all along that Mitt Romney will be the Republican Party's nominee for president. Since his double win last week in Arizona and Michigan, his odds in the prediction markets have jumped above 80 percent. That's likely to go up again after Super Tuesday, since the most likely scenario has Romney winning 7 of the 10 states, Rick Santorum taking 2, and Newt Gingrich winning his home state of Georgia.

The question is whether voters in future primaries decide the race is effectively over after Tuesday and flock to Romney, or whether Santorum lives to fight another day in the polls. A big-enough night for Santorum could prolong his eventual defeat, since polls tend to be more short-sighted than markets. Here are the odds for tomorrow's individual elections:

We can predict with near certainty that Romney will win in Virginia (where only he and Ron Paul are on the ballot), his home turf of Massachusetts, neighboring Vermont, and Idaho. Gingrich likewise has odds of about 95 percent in Georgia.

Romney has 81.6 percent odds in the crown jewel, Ohio, though polls—which lag compared to markets—have him virtually tied with Santorum. (The odds swung significantly in his favor after last week's wins in Arizona and Michigan.) As we've noted before, this literally means that 1 out of 5 times, Santorum pulls off an upset win. Meanwhile, Santorum has 88.6 percent odds in conservative Oklahoma.

That leaves North Dakota and Alaska, where Romney has odds around 75 percent, and Tennessee, where Santorum leads with 57 percent of the vote.

There are 419 delegates at stake Tuesday, and Romney could take the vast majority if he meets or exceeds expectations. The former Massachusetts governor already has an 86.4 percent chance to be the Republican nominee for president, and he will still be the overwhelming favorite to win the nomination regardless of the outcome on Super Tuesday. The question is whether he can effectively seal the deal Tuesday, or leave Santorum enough delegates to hang on to even an imaginary claim to the nomination.

David Rothschild is an economist at Yahoo! Research. He has a Ph.D. in applied economics from the Wharton School of Business at the University of Pennsylvania. Follow him on Twitter @DavMicRot and email him at thesignal@yahoo-inc.com.